At some risk, here is a Kodachrome type film formula for the "last days".
I don't want to be chained in a barn!
In the thread "a real formula" I give an emulsion formula that will make an ISO 25 - 80 emulsion depending on the workers skill and resources. I'll use that as a base to go further.
1. Make 3 emulsions like the one in that thread but use 3 temperatures about 10 - 20 deg C apart. IE, use 40, 60 and 80 deg C for the PPTNs. Then, sensitize each with sulfur or sulfur + gold.
2. You now have 3 emulsions which must be split into 9 jars. Three of them (fast, medium and slow or 80, 60 and 40 deg C makes) will be stored, bu the other 6 will be sensitized spectrally to R and G light. Mixtures of the 3 will be used in each layer. So there will be 3 blues, 3 greens and 3 reds.
3. Find yourself some Rem-Jet backing! Good luck!
4. Coat the red layer (red sensitive) at about 150 mg/ft square of silver using a blend of the three red sensitive emulsions.
5. Coat an interlayer with about 10 mg / ft square of Di-t- octyl HQ. (a scavenger dispersion - see my post on making dispersions....)
6. Coat the magenta (green sensitive layer at about 150 mg / ft square.
7. Coat a mix of yellow CLS silver and 10 mg/ft squre of the HQ dispersion.
8. Coat the unsensitized mix of the 3 emulsions as the blue sensitive layer.
9. Coat a UV absorbing overcoat in gelatin.
10. Go find the couplers and the developing agents and mix the solutions up.
11. Process and adjust the coating and process until you get good color.
Have fun. Don't chain me up in a barn!